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Adjustable pneumatic system for a surgical machine

The present invention relates to a pneumatic module for a surgical machine and more particularly to a pneumatic module with a dynamically adjustable pressure set point.

Vitreo-retinal procedures include a variety of surgical procedures performed to restore, preserve, and enhance vision. Vitreo-retinal procedures are appropriate to treat many serious conditions of the back of the eye. Vitreo-retinal procedures treat conditions such as age-related macular degeneration (AMD), diabetic retinopathy and diabetic vitreous hemorrhage, macular hole, retinal detachment, epiretinal membrane, CMV retinitis, and many other ophthalmic conditions.

The vitreous is a normally clear, gel-like substance that fills the center of the eye. It makes up approximately two-thirds of the eye's volume, giving it form and shape before birth. Certain problems affecting the back of the eye may require a vitrectomy, or surgical removal of the vitreous.

A vitrectomy may be performed to clear blood and debris from the eye, to remove scar tissue, or to alleviate traction on the retina. Blood, inflammatory cells, debris, and scar tissue obscure light as it passes through the eye to the retina, resulting in blurred vision. The vitreous is also removed if it is pulling or tugging the retina from its normal position. Some of the most common eye conditions that require a vitrectomy include complications from diabetic retinopathy such as retinal detachment or bleeding, macular hole, retinal detachment, pre-retinal membrane fibrosis, bleeding inside the eye (vitreous hemorrhage), injury or infection, and certain problems related to previous eye surgery.

A retinal surgeon performs a vitrectomy with a microscope and special lenses designed to provide a clear image of the back of the eye. Several tiny incisions just a few millimeters in length are made on the sclera. The retinal surgeon inserts microsurgical instruments through the incisions such as a fiber optic light source to illuminate inside the eye, an infusion line to maintain the eye's shape during surgery, and instruments to cut and remove the vitreous.

In a vitrectomy, the surgeon creates three tiny incisions in the eye for three separate instruments. These incisions are placed in the pars plana of the eye, which is located just behind the iris but in front of the retina. The instruments which pass through these incisions include a light pipe, an infusion port, and the vitrectomy cutting device or vitrector. The light pipe is the equivalent of a microscopic high-intensity flashlight for use within the eye. The infusion port is required to replace fluid in the eye and maintain proper pressure within the eye. The vitrector, or cutting device, works like a tiny guillotine, with an oscillating microscopic cutter to remove the vitreous gel in a controlled fashion. This prevents significant traction on the retina during the removal of the vitreous humor.

The surgical machine used to perform a vitrectomy and other surgeries on the posterior of the eye is very complex. Typically, such an ophthalmic surgical machine includes a main console to which the numerous different tools are attached. The main console provides power to and controls the operation of the attached tools.

The attached tools typically include probes, scissors, forceps, illuminators, vitrectors, and infusion lines. Each of these tools is typically attached to the main surgical console. A computer in the main surgical console monitors and controls the operation of these tools. These tools also get their power from the main surgical console. Some of these tools are electrically powered while others are pneumatically powered.

In order to provide pneumatic power to the various tools, the main surgical console has a pneumatic module. This pneumatic module conditions and supplies compressed air or gas to power the tools. Typically, the pneumatic module is connected to a cylinder that contains compressed gas. The pneumatic module must provide the proper gas pressure to operate the attached tools properly. Providing different pressures to a tool can alter the way in which it operates over that range of pressures. For example, it is desirable to provide a low gas pressure when a vitrector is operated at a relatively low cut rate, and it is necessary to provide a high gas pressure when a vitrector is being operated at a high cut rate.

It would be desirable to have a pneumatic module that provides a dynamic range of pressures so that the attached tools can be used over their full operating ranges.

In one embodiment consistent with the principles of the present invention, the present invention is a pneumatic system for a surgical machine. The system includes a reservoir, first and second proportional valves, and a controller. The reservoir holds pressurized gas. The first proportional valve is located on an input side of the reservoir and allows a variable amount of pressurized gas to enter the reservoir. The second proportional valve is located on an output side of the reservoir and allows a second variable amount of pressurized gas to exit the reservoir. The controller controls the operation of the first and second proportional valves. The controller adjusts the first and second proportional valves so that a constant gas pressure range is maintained at an output of the reservoir over a first range of input gas pressures and a second range of gas usage.

In another embodiment consistent with the principles of the present invention, the present invention is a pneumatic system for a surgical machine. The system includes a reservoir, first and second proportional valves, a controller, first and second interfaces, and input and output pressure transducers. The reservoir holds pressurized gas. The first proportional valve is located on an input side of the reservoir and allows a variable amount of pressurized gas to enter the reservoir. The second proportional valve is located on an output side of a reservoir and allows a variable amount of pressurized gas to exit the reservoir. The controller is adapted to control the operation of the first and second proportional valves, thereby adjusting an amount of pressurized gas entering and exiting the reservoir. The first interface electrically couples the first proportional valve to the controller. The second interface electrically couples the second proportional valve to the controller. The output pressure transducer is located on the output side of the reservoir, measures a pressure of the pressurized gas exiting the reservoir, and is electrically coupled to the controller. The input pressure transducer is located on an input side of the reservoir, measures a pressure of the pressurized gas near the first proportional valve, and is electrically coupled to the controller. The controller receives a first signal from the input pressure transducer corresponding to the pressure of the pressurized gas near the first proportional valve and a second signal from the output pressure transducer corresponding to the pressure of the pressurized gas exiting the reservoir. The controller uses the first and second signals to adjust the first and second proportional valves so that a constant gas pressure range is maintained in the reservoir over a first range of input gas pressures and a second range of gas usage.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed. The following description, as well as the practice of the invention, set forth and suggest additional advantages and purposes of the invention.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a block diagram of a pneumatically-powered ophthalmic surgery machine according to an embodiment of the present invention.

FIG. 2 is a schematic of a pneumatic system capable of providing a dynamic range of pressures according to an embodiment of the present invention.